We have measured the X-ray reflectivity of rubbed polyimide films used for liquid crystal alignment. Both mechanically rubbed polyimides and polyimides rubbed by linearly polarized UV light were examined. The mechanism for liquid crystal alignment in the optically rubbed films is still unclear; suggested mechanisms include either the formation of large-scale ripples due to anisotropic contraction which in turn interact with the liquid crystal, or reorientation of individual polymer molecules. The mechanical rubbing process creates microgrooves on the surface of the polyimide film, which on average run parallel to the rubbing direction. These grooves result in anisotropic off-specular X-ray reflectivity features. The analysis of the specular reflectivities obtained from these films will produce a comparison of the roughness associated with both mechanically and optically rubbed films, parallel and perpendicular to the rubbing direction. We use specular reflectivity, together with the anisotropic character of our resolution function to extract the anisotropy in the roughness along the film surface. ITEM